Two weeks after its launch, the James Webb Space Telescope completed its assembly in space. The last step was taken this Saturday (8), with the opening and locking of the second wing of its segmented primary mirror. In retrospect, it may have seemed easy. But make no mistake. This was one of the greatest achievements in the history of engineering.
First of all, to recap, what does “completed your montage” mean? The Webb is a telescope with a primary mirror of 6.5 meters that was installed on top of a rocket whose hood was 5 meters. How to put something from 6.5 to 5? doubling. And if it seems difficult to fit 6.5 into 5, think 20. Because the telescope’s heat shield is now that long, comparable to a tennis court, but it had to be placed aboard the Ariane 5 launcher all folded up.
The entire Webb deployment process took place in the last 14 days. From conventional (common to almost all space missions), we had the opening of the solar panels and the propelled trajectory adjustments. But everything else was a complicated space origami unfolding in space, commanded carefully, step by step, from the control room at the STScI (Space Telescope Science Institute), adjacent to NASA’s Goddard Space Flight Center in Baltimore, Maryland. .
More than 300 points in the process lacked redundancy – a failure would mean the mission was lost. The only procedure to try to correct, for example, the tensioning of a layer of the heat shield, would involve shaking the satellite (nothing that could be called a solid plane B).
Everything went well, but the game is still not won. Wasn’t it “30 days of terror”? The schedule still stands. From now on, each of the 18 segments of the primary mirror will have to be individually adjusted. They will be pointed at a reference star and actuators behind them will make small movements to adjust their placement for perfect focus. And then, on the 29th day, another thrust maneuver will put Webb in its final position, following the Earth around the Sun at a distance of 1.5 million km from the planet. But the worst is surely behind us.
Once the critical phase of the flight is over, NASA will move on to commissioning the telescope. Engineers and scientists work together to power up each of the instruments and tune them to perfection. The procedure takes time, partly because of the complexity, partly for physical reasons: the telescope needs to be slowly cooled down to its operating temperature (behind the heat shield it is now at -199°C, but it needs to go to -235° Ç). The whole process is expected to take about five months, at which point Webb will become the newest (and most powerful) space telescope ready for scientific observations. What discoveries await you out there? After seeing it mounted, you can start dreaming about them.
This column is published on Mondays, in Folha Corrida.
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